Lovely Airy.
How did you manage to focus on the DF? I am using mine on a Z6ii, for focus peaking. But one thing we have in common is our choice of subjects :-)
1) DK-17M magnifying eyepiece is a must, irrespective of the lens, when manual focus is the norm. I have fitted all my cameras with it, starting with the D700.
2) A monopod is highly recommended to avoid occasional focussing misses, or general discomfort, due to camera shake when FL exceeds, say, 200mm. It does not matter if it is a light Velbon or a sturdy carbon fiber one; one is far better than none.
Of course, if you are blessed with a Z6 or even with an Olympus OM-D (a nice combo with 180/2.8 for instance), the two points above become irrelevant.
By the way, when using those 500mm mirror lenses, my usual speed is 1/1000s (1 / 2*FL) on static subjects, while I usually set the auto ISO to 1/FL with other lenses. These mirror lenses are relatively light and very short, meaning insufficient inertia. The old 300/4 feels much more stable in comparison...
